1. Field of the Invention
The present invention relates to an apparatus for wideband transmission and reception, capable of transmitting and receiving data by using a plurality of wideband channels or varying a frequency bandwidth, and more particularly, to an apparatus for wideband transmission and reception, which includes a local oscillator (LO) synthesizer providing a constant output to a wideband.
2. Description of the Related Art
A cognitive radio (CR) technology, being recently spotlighted, enables data transmission and reception using frequency resources of a first user without interfering with the first user by monitoring in real time the frequency resources not used by the first user. Not to cause an interference with the first user, when the first user appears in a band in use, a CR system needs to recognize this and move a corresponding channel. In case of institute of electrical and electronics engineers (IEEE) 802.22 supporting the CR technology, data transmission and reception needs to be enabled in a television (TV) band of about 54 MHz to 892 MHz. Additionally, when a TV signal, which is the first user, is detected, the channel in use needs to be promptly changed to another channel. Therefore, a plurality of channels of an extremely wide band are necessary. Here, it becomes difficult to maintain a high signal to noise ratio (SNR) in all the channels compared to in a narrow-band system. In addition, in European computer manufacturers association (ECMA)-392 which is another standard applying the CR technology along with the IEEE 802.22, a flexible transceiver is demanded, which is capable of converting to a 2×2 or higher multi input multi output (MIMO) mode and a multichannel mode based on the conventional single input single output (SISO) mode and varying a signal bandwidth.
In addition, demands for a hardware platform supporting a multiple standard including the CR technology are recently increasing. A data transceiver needs to support ultra wideband characteristics and a flexible bandwidth to support various standards. In a data transceiver using such a wideband channel, an error in amplitude and phase of a baseband in-phase and quadrature (IQ) signal, leakage of carriers of a transmitting and receiving unit, and a direct current (DC) offset need to be controlled for each channel.
Accordingly, there is an increasing desire for a data transceiver having an improved structure maintaining a high performance in a wideband channel and supporting a flexible bandwidth.